where \(s_{ij} \equiv 2 p_i \cdot p_j\) , and \(\mu _{DR}\)  denotes the auxiliary mass parameter of dimensional regularization.
The IR factorization coefficients listed in eq. (REF ) are
extracted from the known singular part of \(\mathcal {A}^{[\text{1-loop}]}_{gggg}(i)\) 
given in ref. [1]}. The IR singular pieces of eq. (REF )
are the same for all IR subtraction methods (for the same renormalized virtual amplitude).
In our consideration the finite remainders of virtual amplitudes are defined by
subtracting all pole singularities of the loop amplitude (REF ) by means of
eq. (REF ). 
